This invention relates to measuring connective tissue breakdown products in a body fluid from an animal.
A breakdown of connective tissue components is believed to be a component of the pathogenesis of some chronic diseases. In chronic obstructive pulmonary disease ("COPD") and in cystic fibrosis ("CF"), for instance, the elastase load in the lungs is increased, and elastin destruction in the lungs is believed to be an ongoing part of the disease process; and proteolytic digestion of lung elastin is thought to be a primary event of the alveolar wall destruction that occurs in the pathogenesis of pulmonary emphysema. In one hypothesis, a sensitive assay for elastin degradation products in urine or blood might provide an indication of the process of alveolar wall destruction. Desmosine ("DES") and isodesmosine ("IDES") are the principal cross-linking amino acids in elastin. Because DES and IDES are unique to elastin, they are recognized as established markers for elastin and elastin degradation products in mammalian tissues and fluids. Moreover, DES and IDES are not metabolized, and are passed directly to the urine, and for these reasons, some attempts to monitor elastin breakdown products as an indication of the condition of the alveolar walls have been directed to measuring urinary desmosine.
Measurements of urinary desmosine ("DES") by means of radioimmunoassay ("RIA"), however, have to date failed to support an elastase-antielastase hypothesis of emphysema, suggesting to some workers a failure of the hypothesis.